Conventionally, an image-processing apparatus has been known in which a means for dividing and compressing image data, a means for storing a group of image data that have been compressed and divided, and a means for restoring the image data by combining and decompressing the group of divided and compressed image data that have been stored in the storing means are installed.
For example, Japanese Laid-Open Patent Application No. 272553/1996 (Tokukaihei 8-272553, published on Oct. 18, 1996) has disclosed an image-processing apparatus wherein: a data memory having unit-based storing area in which one page is divided into P×Q sections with one unit consisting of an M×N matrix area, a compression processing means for storing a bit map image in the storing areas corresponding to the units while storing its pointer in a map memory so as to compress and store the bit map image and a decompressing means for decompressing and outputting the bit map memory in the data memory through the pointer in the map memory are installed so that the bit map image is overwritten on the data memory.
Moreover, Japanese Laid-Open Patent Application No. 142418/1996 (Tokukaihei 8-142418, published on Jun. 4, 1996) has disclosed a printer control device in which: a microcomputer divides print information into a plurality of area, develops each piece of information contained in the divided area so as to store it in a memory, compresses image data that has been held, and stores the compressed image data in the memory, so that decompressed image data is printed.
Here, in digital copying machines, etc. equipped with a storing means which can compress and divide image data corresponding to, for example, a plurality of sheets of original documents, and store the data, the following image processing is required: that is, image data corresponding to a plurality of sheets of original documents are read, and temporarily stored in a storing area of a storing means after having been compressed and divided, and various editing processes specified by the user, such as an “N in 1 editing process” for outputting image data corresponding to N pages (N sheets of original documents) onto one sheet of paper, a “center binding editing process” in which every two pages of a plurality of sheets of original documents are printed on two sides of paper so as to form a book-like shape by binding the center portion thereof, and a “slanted letter” editing process for forming slanted letters, are then carried out.
In such a case, the following processes have to be carried out: the group of divided and compressed image data are combined, decompressed and restored into the original image data on an area other than the above-mentioned storing area or on another storing means (work memory) and these data are subjected to predetermined image processes, and then again stored in the storing area of the storing means after having been compressed and divided.
However, in the above-mentioned Laid-Open Patent Applications, although the descriptions show methods for compressing and dividing image data and for storing it in the storing means, no description is given to the process in which the group of divided and compressed image data are temporarily restored, and then again stored in the storing area of the storing means after having been compressed and divided. For this reason, the following problems are raised:
1) It is considered that normally the group of divided and compressed image data is maintained until the specified image processing has been completely finished, that is, until the image data after the image processing has been compressed, divided and then again stored in the storing means, in case of re-try due to an unexpected trouble, etc.
For this reason, empty storing areas in which the image data after the image processing has been compressed, divided and then stored tend to become insufficient, resulting in interruptions in the image processing.
2) In the case when the divided and compressed image data, temporarily stored in the storing means, are read and subjected to an image-processing including an image combining process such as a center-binding editing process and an editing process for collecting images corresponding to a plurality of pages to one page, the group of divided and compressed image data of respective pages to be combined are joined and decompressed into a processable state on a work memory, and then combined.
Consequently, for example, in the case of a process for collecting images of two pages into one page, the work memory corresponding to a total of four pages is required for the reading process for the respective pages and for the image combining process, with the result that the greater the number of images (the number of pages) to be combined, the greater the work memory required.